Self-supporting gallium nitride single crystal based on HVPE and preparation method thereof

Abstract

The invention provides a preparation method of a self-supporting gallium nitride single crystal based on HVPE, and the method comprises the following steps: (1) providing a substrate, and carrying outthe in-situ cleaning of the surface of the substrate; (2) growing a GaN crystal nucleus on the surface of the substrate at a low temperature, and forming NH4Cl solid from HCl and NH3 at the same timeto compete with the GaN crystal nucleus to cover the substrate; (3) increasing the temperature to 1000 DEG C or above for annealing treatment, and improving the GaN crystal nucleus quality; (4) growing a GaN layer on the GaN crystal nucleus in a medium-high temperature two-dimensional manner; and (5) continuously growing GaN single crystals on the GaN layer at a high temperature; and cooling, andstripping the GaN single crystal from the substrate to form the self-supporting crystal. High-quality nucleation points are provided for growth of self-supporting gallium nitride through HVPE, warping is reduced due to the fact that gaps release stress, cracking is eliminated when growth is finished and cooling is conducted, and the growth yield of the self-supporting gallium nitride is increased.

Description

technical field [0001] The invention relates to the technical field of semiconductors, in particular to a self-supporting gallium nitride single crystal and a preparation method thereof. Background technique [0002] GaN is a typical representative of the third-generation wide-bandgap semiconductors. It has been widely used in semiconductor lighting, microwave power devices, and power electronic devices, showing great application prospects. The most ideal substrate for gallium nitride growth is naturally gallium nitride single crystal material. Such homoepitaxial (that is, the epitaxial layer and the substrate are the same material) can greatly improve the crystal quality of the epitaxial film and reduce the dislocation density. , Improve the working life of the device, improve the luminous efficiency, and increase the working current density of the device. However, gallium nitride single crystal growth is difficult and expensive, and large-scale homoepitaxial growth is sti...

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Problems solved by technology

[0005] However, such methods have disadvantages: 1. High cost, requiring expensive equipment and index processes such as lithography machines or MOCVD; 2. Additional equipment and processes are required, resulting in poor process control performance and reduced yield; 3. Absorbing stress The effect is not very significant

At present, the largest GaN self-supporting substrate in the industry is about 4 inches, which is far from reaching the size of heterogeneous substrates such as silicon, sapphire, and silicon carbide, such as 8 inches or even larger.

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